Effects of Fruiting on Dry Matter Production and Partitioning in Apple Trees Grafted on M.9 Dwarfing Rootstock
1991 Volume 60 Issue 3 Pages 495-503
Details
1991 Volume 60 Issue 3 Pages 495-503
Dry matter production by 'Tsugaru' and 'Fuji' apple trees grafted on M.9 rootstock and planted at distances of 4 m × 2 m was evaluated over 4 growing seasons. The trees were 6 year old at the onset of the experiment.
1. The average dry weight of the scion top portion of 'Tsugaru' trees attained about 70% of that of the vigorous 'Fuji' tops. However, the difference in the weight of the rootstock portion was rather small; the weight of the M.9 stock with 'Tsugaru' top was about 90% of the M.9 stock under 'Fuji' top. Consequently, the scion/rootstock dry weight ratio was smaller in the less-vigorous 'Tsugaru' trees.
2. The average leaf area indices (LAIa) were 1.20 in 'Tsugaru' trees and 2.39 in 'Fuji' trees. The smaller value in the former cultivar may be attributed by fewer current shoots per tree as compared to those of the latter cultivar.
3. The amount of dry matter produced annually during a growing season (DM) ranged from 4, 280 g to 10, 011 g per tree for 'Tsugaru', whereas it ranged from 9, 091 g to 13, 494 g for'Fuji'. There was a higher correlation between the DM and fruit dry weight (F).
4. A higher correlation (r=0.96) existed between the amount of dry matter produced per unit leaf dry weight (DM/L) and fruit-leaf dry weight ratio (F/L) or fruit load, independent of the cultivar. Within the range of the fruit load, DM/L increased from 4.39 g to 7.83 g in 'Tsugaru', and from 4.17 g to 10.27 g in 'Fuji'. There was, however, no difference in DM/L between two cultivars, provided the F/L was comparable.
5. The heavier the fruit load, the greater the proportion of photosynthates which was partitioned to the crop as compared to that partitioned to older wood and shoot. The growth of the older wood and shoot, however, was greater in 'Fuji' than in 'Tsugaru', when the F/L was comparable.
6. An exponentional correlation existed between the DM/L value and leaf area per fruit. Its regression equation is:
Y=35.54X-0.243 (r=0.83)
A similar relation existed between the DM/L and the number of leaves per fruit. Its equation is:
Y=14.69X-0.230 (r=0.84)
